The present invention relates to copending application entitled xe2x80x9cDUAL MODE SATELLITE TERMINAL FOR EMERGENCY OPERATIONxe2x80x9d filed on even date herewith by the same inventor and assigned to the same assignee.
The present invention relates to satellite communication systems and more particularly relates to airborne satellite communications systems and even more particularly relates to airborne satellite communication systems with a satellite antenna mounted on an aircraft at a position other than the top of the aircraft.
In the past, airborne satellite communication systems have been used extensively for aircraft to communicate, via satellite, to terrestrial positions. In many areas of the earth, a typical satellite communications system may have several satellites between which to choose for its communication path. Often these systems make their selection between these several satellites primarily upon the elevation angle of the satellite above the horizon.
While use of elevation angle for satellite selection has some beneficial aspects, especially for top-mounted antennas, it does have serious drawbacks, especially for antennas mounted in positions other than the top of the aircraft.
Consequently, there exists a need for improved satellite communication systems which utilize other than top mounted antennas.
It is an object of the present invention to increase the capacity of airborne satellite communication systems.
It is a feature of the present invention to use side mounted antennas and an algorithm selecting satellites based upon their orthogonality with respect to the plane of the antenna on the aircraft.
It is an advantage of the present invention to increase the effectiveness of satellite communication antennas by improving the cross-sectional area of the antenna capable of capturing signals incident thereon.
It is another object of the present invention to reduce the time required for satellite selection.
It is another feature of the present invention to eliminate the need for mapping each antenna upon initialization of the satellite communication system.
It is another advantage of the present invention to allow airlines to maintain their telephone service in operation for longer time periods, thereby increasing revenues and profits.
It is yet another object of the present invention to provide for a more versatile satellite communication transmitter.
It is yet another feature of the present invention to include a satellite selection feature which will bias the satellite selection based upon particular characteristics of the antenna system in use.
It is yet another advantage of the present invention to reduce reconfirmation expense associated with reconfirming the satellite communication transmitter for differing aircraft installations and antenna characteristics.
The present invention is a method and apparatus for selecting among several available satellites by a satellite communications system, which system includes at least some antennas other than top-mounted antennas which is designed to satisfy the aforementioned needs, provide the previously stated objects, include the above listed features and achieve the already articulated advantages.
Accordingly, the present invention is a method and apparatus including a satellite selection algorithm which utilizes information relating to the types and locations of antennas on the aircraft and to the angle between an antenna normal line and a line to a satellite.